Computational Study of Thermochemistry of Triazolium-Based Dicationic Ionic Liquids

In recent years a substantial growth in the number of theoretical investigations pertaining toionic liquids (ILs) has been occurred. Most of these investigations are concentrated on themonocationic ionic liquids and theoretical studies of the dicationic ILs are scarce. A knowledgeof the enthalpy of formation is an essential requirement to investigate the stability andperformance of these compounds.In this work, the structures of energetic dications are investigated by density functionaltheory (DFT) calculations and Gaussian-3 theory using reduced Moller-Plesset order (G3(MP2))method [1], one of the most successful and widely used composite methods. The G3MP2 methodis found to be accurate in calculating the enthalpies of formations of different classes ofcompounds. The cations considered are the dicationic triazoliums. Two triazolium cations werejoined via a propane linkage chain, [triC3tri]+2. The enthalpies of formation of various substitutedtriazolium cations are predicted by atomization and isodesmic reaction approaches using B3LYPhybrid density functional and 6-311+G(3df,2p) basis set and G3MP2 composite method byGaussian 09 package of program[2]. The computed enthalpies of formation are large and positiveand are dependent on the substituent attached to the two triazolium rings. A good agreementbetween the atomization and isodesmic approaches is evident. Enthalpy of formation isdecreased by the presence of -CH3 and increased by -CN and -NH2 groups.